An exclaimation from HomestarRunner.com. It can be found on the website's 13th menu (Atari-themed)by moving your mouse over the "email" button (Strong Bad screams it), and also by watching the first deleted scene of the Yellow Dello movie (Homestar Runner says it).
Most commonly used as a random quote, and occasionally used to tell an annoying person to get lost.
12 step recovery jargon referring to someone new who talks about how great life is, now that they'resober. Usually meaning that the person is out of touch with reality.
The new guy seems pretty happy for a dude who has no job, no money and no family. He must be on a pink cloud.